1. Field of the Invention
The present invention relates to a ground plane shield device for impedance and cross talk control between signal carrying conductors emanating from an electrical connector, and in particular, to such a shield device adapted for retro-fitting to a connector that has been previously mounted to a board.
2. Description of the Prior Art
Controlling the interfering electrical effect that an electrical signal carried on a given conductor exerts on a signal carried on an adjacent conductor is especially important in high density connectors. Such control can be implemented in a variety of ways. For example, the most basic technique in a high density connector is to connect particular ones of the conductors to a predetermined ground potential, thereby causing such conductors to act similarly to ground planes and thereby to isolate the signals carried on adjacent conductors.
An alternative approach is to provide separate ground plane structures in the connector. Exemplary of this alternative are the devices disclosed in U.S. Pat. No. 4,232,929 (Zobawa) and U.S. Pat. No. 4,558,917 (Kamono et al.). In the latter patent the ground plane structures take the form of separate, spaced vertical plates disposed between adjacent columns of conductor tails emanating from a connector housing. U.S. Pat. No. 3,601,756 (Stroh) discloses a connector in which a ground plane structure is sinuously wrapped about the signal carrying conductors. Copending application Ser. No. 07/067,767,(EL-4258-A) and copending application Ser. No. 07/193,611, (EL-4271-B), both assigned to the assignee of the present invention, relate to shielding schemes for use in cables and in cable connectors.
It is more difficult to control the impedance and crosstalk effects in connectors that have not been previously designed to contain suitable interference control structures once such a connector has been mounted in position on a circuit board substrate.
Accordingly, it is believed to be advantageous to provide a ground plane shield arrangement that is particularly adapted for being expeditiously placed into use with a connector once the same has already been placed in position on a substrate.